WATERTOWN, MASS. As their former chief recounted their firefight with the terrorists who struck the Boston Marathon in 2013, three Watertown police officers were granted the Congressional Medal of Bravery on Friday for their actions more than two years ago.

None of the officers knew they would be encountering two people suspected of bombing the Boston Marathon, said Ed Deveau, who recently retired as Watertown police chief. The two brothers caused murder and mayhem with two pressure cooker bombs on Boylston Street. Days later as grainy images of the two blanketed news media, they murdered MIT police officer Sean Collier and hours after that encountered Watertown police the night of April 18, 2013.

Tamerlan Tsarnaev died at the scene in Watertown, and his younger brother Dzhokhar Tsarnaev was sentenced to death after a federal trial earlier this year.

“The real story hasn’t been told, detail by detail, blow by blow, what these three guys did to protect Watertown,” Deveau said at a ceremony at Watertown Police Station Friday.

In attendance was U.S. Attorney Carmen Ortiz whose prosecutors secured the convictions and death verdict against Dzhokhar, as well as Middlesex District Attorney Marian Ryan who may bring state charges against Dzhokhar at a later date.

Officer Joseph Reynolds was the first on the scene on Laurel Street. After Tamerlan charged and shot at him, Reynolds leaned down and reversed his cruiser toward relative safety.

“He had no idea what it was going to be up against. He thought it was just a carjack vehicle out of Cambridge. He didn’t know he was going to meet the Boston bombers,” Deveau said.

Next on the scene was Sgt. John MacLellan, the supervisor on the street that night, who came around the corner onto Laurel Street when Reynolds was in “full reverse,” Deveau said. A hot bullet “lit up” Reynolds’s ear and landed in the car’s headrest, Deveau said.

Under fire, Reynolds rolled his car down the street and ran behind a tree, Deveau said, as the first pipe bomb thrown by the bombers shattered the windows of the cruiser.

“For over four minutes it was just John and Joe on that back street in Watertown … ,” Deveau said.

The two officers took cover behind the tree as one of the next responding officers – Sgt. Jeffrey Pugliese, who had been on his way home in his family minivan – decided to come to their aid.

When Pugliese heard the firing, the military veteran and Watertown police firearms instructors decided to try to “go through some backyards and try to flank” the two perpetrators.

A bomb made from a pressure cooker exploded in the street, filling the air with particles as Pugliese made his way toward the scene. Pugliese encountered a resident running from a nearby home.

“It could have easily been one of the suspects, and I talked to Jeff later and I said, ‘Jeff, how come you didn’t shoot?'” said Deveau who praised Pugliese’s decision to hold his fire. “He said, ‘Chief, I could see his hands, and I don’t think he had a firearm. I thought it was one of the terrorists, but he was running away – that was good for us.’ ”

As Pugliese got closer and began to engage with the Tsarnaevs, he “used his calmness and courage to skip-shoot bullets under the vehicle” hitting Tamerlan at least once. With only 10 or 15 feet separating them, Pugliese and Tamerlan exchanged gunfire.

Tamerlan was eventually killed and in the gun battle, Transit police officer Dic Donahue was seriously injured.

Amid the chaos of the scene, Dzhokhar escaped, hiding for a time in a boat in a Watertown backyard as the town filled with law enforcement hunting for him through most of the next day.

Former Sen. Warren Tolman, who has said the police response in his town encouraged him to run for attorney general, was at the ceremony as were U.S. Sens. Elizabeth Warren and Ed Markey and U.S. Reps. Joe Kennedy and Katherine Clark.

Ryan has preserved her right to bring state charges against Dzhokhar, a move that some have criticized.

“I have every confidence in the integrity of the proceedings in the federal court, but we are preserving our rights. Do I anticipate this is going to happen anytime soon? No, I don’t,” Ryan told the News Service after the event. She said, “Good lawyering is preparing for the unexpected.”

Asked if her move would allow state charges in the event that any of the federal convictions are overturned on appeal, Ryan said, “We are preserving our rights if that ever became necessary.”